Process for preparation of resin-coated molding sand

Abstract

The process for preparing a resin-coated casting sand by coating sand grains with a binder comprising a liquid phenolic resin component and a polyisocyanate component, the improvement of which comprises coating sand grains with an organic solvent prior to coating of the sand grains with the binder, thereby prolonging the bench life of the resulting resin-coated casting sand and enhancing the strength of a casting mold prepared from this resin-coated casting sand. Furthermore, this process enables the utilization of sand of a low grade or reclaimed sand having a high alkaline component content, that has not been used in the conventional process, and the supply of an excellent resin-coated casting sand which is capable of providing a casting mold having a high strength and has a long bench life.